Pulse generator

ABSTRACT

An electrical pulse generator comprising a fixed coil with an odd number of sets of pole piece fingers thereon is provided in association with a rotatable magnet having a different odd number of sets of pole piece fingers thereon and extending therefrom for operative association with and rotation by the pole piece fingers extending from the coil for creating pulses therein as a wheel in which the magnet is usually positioned is rotated.

United States Patent inventor Theodore Frayer North Canton, Ohio Appl.No. 4,552 Filed Jan. 21, 1970 Patented Aug. 17, 1971 Assignee TheGoodyear Tire & Rubber Company Akron, Ohio PULSE GENERATOR 5 Claims, 2Drawing Figs.

0.8. Ci. 310/156, 3 10/ l 64 Int. Cl ..1102k 21/16 Field of Search .5310/67,

[56] References Cited UNITED STATES PATENTS 1,333,119 3/1920 Krag-Muller310/156 X 2,882,427 4/1959 Hils et a1.... 310/67 2,985,778 5/1961 Fritz310/41 3,403,273 9/1968 l-liguchi 310/41 Primary Examiner-D. X. SlineyAttorneys-F. W. Brunner, P. E. Milliken and Oldham &

Oldham ABSTRACT: An electrical pulse generator comprising a fixed coilwith an odd number of sets of pole piece fingers thereon is provided inassociation with a rotatable magnet having a different odd number ofsets of pole piece fingers thereon and extending therefrom for operativeassociation with and rotation by the pole piece fingers extending fromthe coil for creating pulses therein as a wheel in which the magnet isusually positioned is rotated.

PULSE GENERATOR This invention relates to a pulse generator, ortransducer particularly adapted to be associated with a vehicle wheelbrake antiskid system and wherein the pulse generator will provide alarge number of pulses per' rotation of the wheel to be controlled tomeasure the speed thereof.

PRIOR ART I-Ieretofore there have been various types of pulse generatorssuch as transducers provided and they have been designed for varioususes. In the control of skidding in vehicle wheels, and particularly inaircraft, it is very desirable that a very rapid speed indication signalbe provided to show when a skid situation is developing. To achieve theproper type'of control, it is highly desirable that a large number ofpulses be provided per wheel rotation and that these pulses be fed toproper control circuitry to effect the desired control action. The priorart has used various methods and apparatus to indicate -by a frequencymeasurement the speed of rotation of the wheel. For example, U.S. Pat.No. 3,017,145 teaches utilization of an electrical generator adapted forsensing wheel rotation which utilizes pennanent magnets and a polerelationship to obtain frequency. U.S. Pat. No. 3,233,946 teachesutilization of a proximity coil with pole pieces to measure wheelrotation. While these prior systems have functioned relatively'efiectively in many instances, it is desirable to provide an improved,relatively inexpensive pulse generator for use particularly in antiskidcontrol apparatus and to provide asturdy, mechanically sound, compactapparatus for pulse generation that can be used to indicate changes inwheel speeds.

It is the general object of the present invention to provide an improvedpulse generator which is relatively inexpensive, compact, and thatprovides a long service life with minimum maintenance. 1

Another object of the invention is to generate a large number of pulseswith relatively few pole pieces.

Another object of the invention is to provide a relatively small fixedcoil with a pair of pole pieces having a plurality of axially extendingpole piece fingers thereon andto provide a rotatable permanent magnetassembly having a pair of pole pieces having'a plurality of axiallyextending pole piece fingers thereon positioned for rotating in-theplane of the pole piece fingers of the fixed coil to provide a variablemagnetic coupling therebetween with rotation of the rotatable magnetassembly.

A further object of the invention is to utilizean odd number of poleteeth on a pair of pole pieces in a transducer in a fixed coil portionthereof and a different butodd number of teeth on a pair of pole pieceson arotatable magnet assembly provided in operative association with thefixed pole teeth to provide an electrical voltage pulse for each angularmotion equal to the difierential circumferential spacing between thepole teeth on the difierent pole pieces in thetransducer.

For a better understanding of the invention, reference should be had tothe accompanying drawings, wherein:

FIG. 1 is a vertical cross section of an axle and wheel combinationincluding the pulse generator of the invention; and

FIG. 2 is a diagrammatic vertical section, taken on line 2-2 of FIG. 1,to indicate the relative circumferential positioning and spacing of thepoles in the pulse generator of FIG. 1.

When referring to corresponding members shown in the drawing andreferred to in the specification, corresponding numerals are used tofacilitate comparison therebetween.

SUMMARY OF THE INVENTION To achieve the present invention, a pulsegenerator is provided comprising a housing with-a fixed coil positionedtherein, and with a pair of pole pieces individually abutted againstdifferent sides of the coil with the pole pieces each having the samebut an odd number of axially extending fingers thereon at the peripheryof the coil and extending therefrom in the same direction. These fingersare alternately positioned in uniformly circumferentially spacedrelation to. each other. A rotatable member is operatively aligned withthe axis of the housing, and a permanent magnet, with a pair of fiatfaces of opposite polarity, is carried by the rotatable member. A fiatpole piece is positioned against each face of the pennanent magnet andhas an odd number of pole 'piece fingers extending therefrom towardssaid housing-and with the fingers of the magnet pole piecesbeingalternately positioned in uniformly circumferentially spacedrelationship to each other. Such magnet pole piece fingers arepositioned radially within the pole piece fingers of the coil polepieces whereby on rotation of the rotatable member, a large number ofelectrical pulses are obtained in the coil per revolution, which pulsescan be used for measuring the rotational speed of such rotatable member.

In general, the pulse generator of the present invention particularly isuseful in antiskid braking systems wherein it is necessary to sense,accurately and instantaneously, the present rotational speed of a wheelto sense properly when it is approaching skid conditions so thatsuitable antiskid circuitry can beactuated to control braking action andavoid skidding conditions.

In the accompanying drawings, a wheel 10 is indicated that is journaledon anaxle 11 by bearings 12 and 13, or equivalent means.

The pulse generator, or transducer of the invention, is adapted to becarried operatively by the axle 11, and thus a suitable housing 14,usually tubular, and which is made from nonmagnetic material, is securedwithin the axle 11 usually at an end thereof by a suitable member suchas a cap screw 15. This housing 14 has a conventional connector memberor socket 16 secured theretowith a pair of leads l7 and 18 extendingtherefromand connecting to a coil 19 received within a counterboredsection 20 of the housing 14. Normally, the core opening of this coil 19has a soft iron core or magnetic member 21 positioned therein to providea low reluctance path for the flow of electromagnetic flux therethrough.I

A pair of spiderlike, good flux conducting pole pieces 22 and 23 areindividually abutted against the opposed side faces of the coil 19 andthe ends of the member 21, as indicated in the drawings, and these polepieces 22 and 23 have a plurality of odd in number sets of pole piecefingers or sections 24 and 25 extending axially therefrom atthepe'riphery of the coil 19. It will be seen that the fingers 24 henceare axially longer than the fingers 25 but with all of such fingers 24and 25 being positioned at a uniform radial distance with relation tothe centerline of the housing 14 and protruding axially beyond the planedefined by the coil 19. This coil 19 and pole pieces 22 and 23 can besecured in position in the housing 14 in a conventional manner, as bypotting such members in the counterbore 20 by conventional resins orequivalent materials.

In order to provide induced electrical impulses in the coil 19, apermanent magnet means isprovided in operative association with thewheel 10 for rotation with relationship to the coil 19 and the polepieces and pole piece fingers provided thereon. Hence, any conventionaltype of a wheel cover C is provided that has a center member or section26 thereon and which center member 26 is secured to the wheel 10 forrotation therewith asby cap screws 27 engaging a flange portion of themember 26. A suitable permanent magnet 28 is provided and it is made ofdisc shape with opposed north and south poles provided on the oppositefaces thereof as indicated in the drawings. The magnet 28 isrelativelythin axially but yet provides an effective electromagneticfield for use in inducing electrical impulses in the coil 19, as laterdescribed. This permanent magnet 28, having flat faces 29 and 30thereon, has any known magnetizable material therein, and the magnet canbe made of any available diameter such as will fit readily into thecounterbored end 20 of the housing 14.

Similar to the pole pieces 22 and 23, a pair of magnetic pole pieces 31and 32' are provided and are suitably operably secured adjacent andabutting against the end faces 29 and 30 of the magnet 28. These polepieces are similar to those described hereinbefore and are of spiderlikenature. An odd number of axially extending sets of substantially flatfingers or sections 33 and 34 are provided on each of these pole pieces31 and 32, respectively. The fingers 34 on the pole piece 32 are axiallylonger than the similar fingers 33 provided on the pole piece 31, butwith both of such sets of polepiece fingers extending axially a shortdistance beyond the adjacent face 29 of the permanent magnet 28. Thepole piece fingers 33 and 34 are uniformly spaced and are alternatelypositioned circumferentially,but being at a common radius with relationto the center axis of the axle 11 soas to be received within the polepiece fingers 24 and 25 so as to rotate immediately adjacent to thefixed coil fingers.

FIG. 2 of the drawings shows the pole piece fingers 24 and 25 inrelation to the pole piece fingers 33 and 34 whenseven teeth or fingersare provided on each of the pole pieces 22 and 23 and when three teethor fingers are provided on each of the pole pieces 31 and 32. Withparticular configuration, a pulse will be obtained on each arcuatemovement of the wheel corresponding to the differential between thecircumferential spacing of the pole piece fingers 24 and with relationto the circumferential spacing of the pole piece fingers 33 and 34.Specifically, if seven teeth are provided on each of the pole pieces 22and 23 and with three teeth on each of the pole pieces 31 and 32, thenthe spacing will be as shown in FIG. 2 and a pulse will be obtained inthe coil 19 with each alignment of the rotating and stationary fingers,thus making a pulse for every one forty-second of a wheel rotation.Alternate pulses will have opposite polarity.

It will be realized that these electrical impulses are provided in thecoil 19 by operation of Lenzs Law, wherein the reluctance of the coil 19in association with its pole pieces 22 and 23 changes each time oneofthe pole piece fingers 33 or 34 passes by one of the fingers 24 or 25on the pole pieces 22 and 23 whereby an induced current is producedeither of a plus or a minus direction depending upon the relativepolarities of the pole piece fingers being moved immediately adjacentand past each other.

Obviously the pulses generated in the transducer or pulse generator ofthe invention can be readily transmitted from the connector 16 to anytype of a control circuit and with such pulses then being measured andbeing compared as to frequencies required to set up skid conditions inrelation to the then permitted amount of braking action in the systemwhereby the transducer or pulse generator can be used readily inantiskid control systems.

The pulse generator of the invention is quite compact, and can fit intorelatively small diameter axles 11 and with the permanentmagnet 28having a very short 'axial length so that a compact, but sturdy systemcan be provided that will effectively indicate wheel speed substantiallyinstantaneously.

While any suitable number of pole piece fingers can be provided in thetwo pairs of pole pieces 22 and 23, and 31 and 32 provided inassociation with the coil 19 and magnet 28, respectively, it isnecessary that the number of pairs of sets of fingers in each pair ofpole pieces be odd in number and with the number of sets of north andsouth fingers on the magnet pole pieces being different in odd numberfrom the odd number of sets of corresponding fingers on the coil polepieces. Usually a minimum of three pole piece fingers on the permanentmagnet assembly would be satisfactory in association with seven polepiece fingers on each of the pole pieces of the fixed coil, butpreferably even a larger number of pole piece fingers are desired sothat seven pole piece fingers on each pole piece of the coil and fivefingers on each pole piece 31 and 32 of the permanent magnet, at least,are desired, but with higher units of such pole piece fingers beinguseful in some instances. Such constructions provide the required highquantity of pulses per revolution.

The housing 14 cover 26 preferably are made from non- What I claim is:

1. A pulse generator comprising a housing having a longitudinal axis,

a fixed coil positioned in said-housing,

a magnetic core in the bore of said coil,

a pair of fiat pole pieces one of which is adjacent each side of saidcoil and an end of said core, said pole pieces each having a pluralityof axially extending fingers thereon at the periphery of said coilextending in the same direction and being alternately positioned inuniformly circumferentially space relation, each adjacent pair of suchfingers forming a set and an odd number of sets of such fingers beingprovided, i I

a rotatable member operatively aligned with the axis of said housing, i

a permanent magnet having a pair of flat faces of opposite polaritycarried by said rotatable member, and

a flat pole piece positioned against each face of said permanent magnetand each side of said coil, both of said second-named pole pieces havinga plurality of axially extending fingers thereon, the fingers of thepair of magnet pole pieces being alternately positioned inuniformlycircumferentially spaced relation, each adjacent pair of such fingersforming a set and an odd number of sets of such fingers being provided,a different number of sets of said fingers on the coil pole pieces beingprovided than on the magnet pole pieces, said fingers on the twodifferent pairs of coil and magnet pole pieces being immediatelyradially adjacent whereby on rotation of said member a large number ofelectrical pulses are obtained in said coil per revolution.

2. A pulse generator as in claim 1 where a permanent magthereon at theperiphery of said coil extending in the same direction and beingalternately positioned in uniformly circumferentially spaced relation,

a rotatable member operatively aligned with the axis of said housing,

a permanent magnet having a pair of flat faces of opposite polaritycarried by said rotatable member, and

a flat pole piece secured to each face of said permanent magnet, each ofsaid last-named pole pieces having an odd number of axially extendingfingers thereon at the periphery of said magnet extending in the samedirection and being alternately positioned in uniformlycircumferentially spaced relation, said second-named pole pieces havinga different number of said fingers thereon than said first-named polepieces, said second-named pole pieces being positioned immediatelyradially adjacent said first-named pole pieces whereby on rotation ofsaid member a large number of electrical pulses are obtained in saidcoil per revolution.

4. A pulse generator as in claim 3 where at least seven fingers areprovided on said first-named pole pieces, and at least five fingers areformed on said second-named pole pieces.

5. In combination with a wheel rotatably mounted on an axle, atransducer comprising a housing secured to said axle,

a coil positioned in said housing,

a magnetic core in the bore of said coil,

a pair of flat pole pieces one of which is adjacent each side of saidcoil and has a section adjacent an end of said core, said pole pieceseach having an odd number of axially extending fingers thereon at theperiphery of said coil extending in the same direction and beingalternately positioned in uniformly circumferentially spaced relation,

gets being provided on said second-named pole pieces than on saidfirst-named pole pieces, said second-named pole pieces being positionedimmediately radially adjacent said first-named pole pieces whereby onrotation of said wheel a large number of electrical pulses are obtainedin said coil per revolution, and

leads connecting to said coil to transmit electrical signals therefromto a remote point to measure wheel rotational speed.

1. A pulse generator comprising a housing having a longitudinal axis, a fixed coil positioned in said housing, a magnetic core in the bore of said coil, a pair of flat pole pieces one of which is adjacent each side of said coil and an end of said core, said pole pieces each having a plurality of axially extending fingers thereon at the periphery of said coil extending in the same direction and being alternately positioned in uniformly circumferentially space relation, each adjacent pair of such fingers forming a set and an odd number of sets of such fingers being provided, a rotatable member operatively aligned with the axis of said housing, a permanent magnet having a pair of flat faces of opposite polarity carried by said rotatable member, and a flat pole piece positioned against each face of said permanent magnet and each side of said coil, both of said second-named pole pieces having a plurality of axially extending fingers thereon, the fingers of the pair of magnet pole pieces being alternately positioned in uniformly circumferentially spaced relation, each adjacent pair of such fingers forming a set and an odd number of sets of such fingers being provided, a different number of sets of said fingers on the coil pole pieces being provided than on the magnet pole pieces, said fingers on the two different pairs of coil and magnet pole pieces being immediately radially adjacent whereby on rotation of said member a large number of electrical pulses are obtained in said coil per revolution.
 2. A pulse generator as in claim 1 where a permanent magnet is used and said housing and member are made from nonmagnetic material.
 3. A pulse generator comprising a fixed housing, a fixed coil positioned in said housing, a soft iron core in the bore of said coil, a pair of flat pole pieces one of which abuts on each side of said coil and an end of said core, said pole pieces each having an odd number of axially extending fingers thereon at the periphery of said coil extending in the same direction and being alternately positioned in uniformly circumferentially spaced relation, a rotatable member operatively aligned with the axis of said housing, a permanent magnet having a pair of flat faces of opposite polarity carried by said rotatable member, and a flat pole piece secured to each face of said permanent magnet, each of said last-named pole pieces havIng an odd number of axially extending fingers thereon at the periphery of said magnet extending in the same direction and being alternately positioned in uniformly circumferentially spaced relation, said second-named pole pieces having a different number of said fingers thereon than said first-named pole pieces, said second-named pole pieces being positioned immediately radially adjacent said first-named pole pieces whereby on rotation of said member a large number of electrical pulses are obtained in said coil per revolution.
 4. A pulse generator as in claim 3 where at least seven fingers are provided on said first-named pole pieces, and at least five fingers are formed on said second-named pole pieces.
 5. In combination with a wheel rotatably mounted on an axle, a transducer comprising a housing secured to said axle, a coil positioned in said housing, a magnetic core in the bore of said coil, a pair of flat pole pieces one of which is adjacent each side of said coil and has a section adjacent an end of said core, said pole pieces each having an odd number of axially extending fingers thereon at the periphery of said coil extending in the same direction and being alternately positioned in uniformly circumferentially spaced relation, a member operatively secured to said wheel and operatively aligned with the axis of said housing, a permanent magnet having a pair of flat faces of opposite polarity carried by said rotatable member, a flat pole piece positioned over each face of said permanent magnet, each of said last-named pole pieces having an odd number of axially extending fingers thereon at the periphery of said magnet extending in the same direction and being alternately positioned in uniformly circumferentially spaced relation, a lesser number of fingers being provided on said second-named pole pieces than on said first-named pole pieces, said second-named pole pieces being positioned immediately radially adjacent said first-named pole pieces whereby on rotation of said wheel a large number of electrical pulses are obtained in said coil per revolution, and leads connecting to said coil to transmit electrical signals therefrom to a remote point to measure wheel rotational speed. 